1. Technical Field
The present invention relates to a control device for preventing meandering of patterns which enables to mark patterns on exact positions on a film.
2. Related Art
Along with an explosion in demands for high-definition three-dimensional displays, demands for precise patterned optical films also increases. The patterned film can be manufactured by, for example, forming patterns on a sheet-typed base film as described in JP 2003-337226. However, in many cases, considering manufacturing, etc., the patterned film is manufactured by forming patterns on a roll-typed base film while the film is steadily being unrolled.
Meandering of patterns occurs for various reasons. For example, the central axis of the film can be deviated when the film has not been properly rolled. Even if the film has rolled properly, the meandering can occur when the film is not properly balanced or an external force is applied to the film.
Regardless of the reason, the meandering causes defects in quality of films because when the meandering occurs, it is unable to form precise patterns on a film. FIG. 1A shows that a pattern forming apparatus forms patterns on a constant position regardless of the meandering, and FIG. 1B shows an actual trace of the patterns on the film which has been formed in FIG. 1A.
Moreover, especially when manufacturing patterned films for three-dimensional display, inaccurate patterns can cause problems for constructing proper three-dimensional images.
An edge position controller (EPC) is usually used for preventing meandering of the patterns. However, there are limits for forming patterns at the micrometer level because the EPC can control the position of the patterns only at the millimeter level.
Meanwhile, there was another method for recognizing meandering of patterns by comparing distances between formed patterns on the film, however, this method can detect the meandering only after the patterns are formed. Therefore, a new technology for detecting meandering of patterns in real-time is needed.